Shango is right. Il pizzaiolo is a really amazing full menu italian restaurant, and its the best neapolitan pizza I have had in the US (along with UPN on a good day). I think that Ron's pizza is more consistent, though. Do yourself a favor and go twice, once for pizza and an app, and another time for other non pizza menu offerings. Ron is bringing in ingredients that are 100% authentic and the best you can buy to make his highly studied menu. Its honestly just like eating in Italy in quality with authentic techniques/recipies for every dish.
Other interesting pizza in the area is Vincents pizza park (a few locations) for some of the best non neapolitan pizza around. Its pretty much new york style, but done with a blend of smoked provolone and mozzarella with lots of cheese and sauce. Its sloppy, yet addictive pizza. Mineo's is the other popular pizzeria in town and also good, but for me not quite as good as vincents. This is a great town to sample sicilian style pizza. I grew up with mama lucias which is excellent, but I have heard great things about other sicilian in the burgh, so if you see some that looks good try it.
Primanti brothers sandwiches in the strip district is a pittsburgh classic that should not be missed.